The English don't really seem to understand Northern Ireland (maybe the rest of the world doesn't either, but I don't get exposed to them as much). I was born in Northern Ireland and lived there until I went to university in England. I still go back there several times a year as my family live there.
The first indication I remember that something was wrong was when I tried to buy car insurance for the first time. I was living in England (car insurance in Northern Ireland is more expensive, and most of the online options won't cover it; I understand this is because injury claims are [or possibly used to be] awarded by jury there, as opposed to by a judge on the mainland. Juries apparently are likely to award more.), and when I was asked if I'd lived in the UK all my life I said yes. Except they knew about me being from Northern Ireland or something (I'd probably asked about being covered for driving back there) and claimed that it wasn't part of the UK. And when I said that yes it was they fell back to "but it hasn't always been". Er, yes, it has. For as long as Northern Ireland has existed as an entity distinct from the rest of Ireland it's been part of the UK. And it's been part of the UK since 1801 anyway. Long before I was born thankyouverymuch.
Since then there have been minor incidents; for example the Post Office clerk not being sure if it cost more to send things to Northern Ireland (she got corrected by one of her coworkers though, and I know that sometimes they won't guarantee delivery times so I forgive her that).
Today I get asked by a friend if Northern Ireland is part of the UK phone network. WTF? Yes. It is. It's part of the UK. No, really. I'll say that again so it sinks in. Northern Ireland is part of the UK. BT are the monopoly telephone provider there. 3, O2, Orange, T-Mobile and Vodafone all provide service there. You don't need a magically different mobile phone contract (the person in question was particularly interested in short codes) if you live in NI rather than mainland UK. Gah. What are these people taught?
(I didn't confuse the issue when explaining to my friend about NI being part of the UK by saying that some call charges do differ; last I investigated ringing Ireland from Northern Ireland with a BT line was the same price as ringing the rest of the UK. Equally it was cheaper to ring NI from Ireland than to ring the rest of the UK. My information is several years old now as I tend to just use my mobile when I'm back there. There's also the oddity about dual citizenship; anyone born in NI has the right to Irish citizenship as well if the choose. Oh, and while I'm ranting, why is the adjective for someone from the UK "British"? Britain doesn't cover all of the UK. I wasn't born in Britain yet I'm British. Can't I be UKish or something?)